Buy Two, Get One: De Novo IBD Onset Following Kidney Transplant and Immunosuppression

Introduction: De novo IBD is a rare complication following solid organ transplantation. Other post-transplant gastrointestinal complications like cytomegalovirus (CMV) colitis or mycophenolate mofetil (MMF) colitis are more likely; therefore, de novo IBD is a diagnosis of exclusion. Case Description/Methods: A 55-year-old man with a history of deceased donor kidney transplant in 2017, presented with chronic diarrhea in 2021. His maintenance immunosuppression included tacrolimus, MMF and prednisone. Stool studies for C. difficile, parasites and infectious agents were negative. A colonoscopy performed 3 weeks after presentation was unremarkable, and biopsies were negative for CMV, IgA, IgA TTG and histologic abnormalities. Esophagogastroduodenoscopy was negative. Given the concern for MMF colitis, MMF was withheld for 1 year; however, there was no improvement in the diarrhea. Four months after symptoms started, CT abdomen showed distal and terminal ileum prominent fold pattern with mild wall thickening, and reversal of the jejunoileal fold pattern. A repeat colonoscopy 5 months after diarrhea onset revealed tiny clean-based ulcers starting at the distal rectum and scattered throughout the colon, with larger ulcers at the terminal ileum (Figure 1). Ulcer biopsies showed patchy moderate nonspecific chronic colitis. Immunostaining for CMV remained negative. Topical budesonide led to no clinical improvement. A new diagnosis of de novo Crohn's disease was favored, and the patient was started on risankizumab 360 mg/2.4 mL injection every 8 weeks. The patient reported that diarrhea dramatically improved. MMF was reintroduced with no relapse. Discussion: There are only 46 reports of ulcerative colitis or Crohn’s presenting de novo IBD. The mean time after transplantation to de novo IBD presentation is 4.6 years with cases showing macroscopic and microscopic findings on first colonoscopy. However, this patient showed an atypical presentation in which 4 years after transplant, initial colonoscopy was negative. Five months after diarrhea onset, a repeat colonoscopy exhibited delayed findings of ulcers and histologic colitis. Therefore, albeit rare, de novo IBD could be a concern for post-transplant onset IBD. Empirical studies have shown improvement through reduction of corticosteroids, MMF, and/or tacrolimus. Paradoxically, this case study presents de novo IBD that responds well to additional immunosuppression of risankizumab, an IL-23 antagonist for Crohn’s disease, rather than reduction of immunosuppressive therapy.Figure 1.: Colonoscopy images of (A) ileitis (B) ileitis (C) colitis (D) rectal ulceration.